R/E/P Community

Please login or register.

Login with username, password and session length
Advanced search  

Pages: 1 [2]  All   Go Down

Author Topic: Surround?  (Read 4045 times)

StudioRhythm

  • Jr. Member
  • **
  • Offline Offline
  • Posts: 71
Re: Surround?
« Reply #15 on: November 15, 2007, 11:21:49 am »

Thanks for all the info, Fran and Jay. Very helpful -- there certainly seem to be a lot of options out there!

Are there any papers/books/test results that might be good places to research these type of traps, or any way to quantify exactly what they're doing (and how?) Having never built or seen anything like this, I just don't have any sense for how a 4' deep trap of this type would compare to just filling the whole thing with insulation, and it'd be interesting to know more about how these hanging traps function.

Thanks again for sharing your time and knowledge, it's very much appreciated! (as is all "the good stuff"...!  Very Happy )

gullfo

  • Full Member
  • ***
  • Offline Offline
  • Posts: 133
Re: Surround?
« Reply #16 on: November 15, 2007, 01:05:55 pm »

i believe that actual math used to reliably predict the performance of these type of hanging baffle traps is limited to some basic 1/4 wavelength definitions related to the hanging and baffle lengths, as well as the cavity properties (pressure and velocity). beyond that (and someone feel free to divulge it  Rolling Eyes ), its mostly "rule of thumb" type stuff, you would have to build it, measure it, and adjust it to get the desired response characteristics.
Logged
Glenn Stanton

www.runnel.com/

franman

  • Hero Member
  • *****
  • Offline Offline
  • Posts: 580
Re: Surround?
« Reply #17 on: November 18, 2007, 11:08:12 am »

Trap bandwidh is basically limited by 1/4 wavelength depth (or width if you want to look at low angle of incidence action)... there is no 'magic' to the baffle spacing IMHO. I've seen people 'tweek' these and say that they are tuning the bass traps??? I tried on at least three projects to measure the response at the trap (and the room) as we moved the baffles closer to and further away from eachother.. I could tell no difference. These are just large areas of porous absorption that are free to move easily thus allowing the friction to be converted efficiently to heat... that's how I it. so we space them ____ inches apart... (there has to be some mystery left after this forum, right??) Cool  Cool
Logged
Francis Manzella - President, FM Design Ltd.
                 - Managing Director, Griffin Audio
fmdesign.com
griffinaudiousa.com

gullfo

  • Full Member
  • ***
  • Offline Offline
  • Posts: 133
Re: Surround?
« Reply #18 on: November 18, 2007, 01:19:16 pm »

there doesn't seem to be much info regarding "hangers" (ala Tom Hidley). here's the response from Jeff Cooper when I was asking about the broadband absorbers on p.49 of his book "Building a Recording Studio" http://www.amazon.com/Building-Recording-Studio-Jeff-Cooper/ dp/0916899004

Quote:

From our experience, broadband traps have an effective low frequency cutoff equal to 1/7th of the wavelength absorbed. To compute this, measure the total panel length (i.e. L+S where L is the panel size and S is the hanger size per the diagram in the book) and use the formula on p.5 for wavelength.

For example, a ceiling hung trap constructed of free-hanging fiberglass-covered panels, each measuring 24" long, on 6" hangers (total length = 30" or 2.5 feet) would be effective above 2.5' x 7 = 17.5' Effective cutoff wavelength 2.5 x 7 = 17.5 ft. (per formula on p.5) Frequency = V/l = 1130/17.5 = 64.5 Hz

As long as the entire cavity was lined with absorptive materials and the trap blankets were at least 12" on center, this trap would be effective at all frequencies above 64.5 Hz.  To decrease the cutoff frequency and make a basstrap effective down to 40 Hz, the panel length would need to  be approximately 4 ft. long (including hangers). Very often, this type of broadband trap is constructed with  varying sized panels, giving a more contoured absorption curve.  An exact formula, relating panel spacing, size, hanger depth, etc. is empirical and not readily available.

Logged
Glenn Stanton

www.runnel.com/

Sonovo

  • Sr. Member
  • ****
  • Offline Offline
  • Posts: 267
Re: Surround?
« Reply #19 on: November 18, 2007, 03:13:11 pm »

A few more questions about the setup and room.

I spoke with an acoustician and a designer, and one suggestion that I really liked involved expanding the size of the room. Before I do it, I'd like to hear any comments people here might have.

Basically there is a 'wall' of closets that divides the room in two parts, the main studio and a smaller kitchenette/office area.

The suggestion was to tear down the closets, and instead put up shelves/closets on what will be the new rear wall.

I'm thinking that this is going to change the room nodes as the room's proportions will be changed. However, it might be positive as it will place the rear wall much farther from the listening position (currently about 1.5m, after removing closet divider it will be about 4m).

I also think it will make placement of the rear speaker channels much easier than my current setup.

Current dimensions:

width: 5m 70cm
length: 7m 50cm (created by a wall of ceiling height closets)
height: 2m 50cm

Expanded dimensions:

width: 5m 70cm
length: 10m 20cm (closets removed)
height: 2m 50cm

It was also suggested to put tracks in the ceiling where the closets are now and hang acoustic panels that can be used as a kind of room divider (as well as absorbing much of the rear reflections) or opened up, depending on the work being done. I don't know if this would have any real effect, or if there are any products that would be appropriate and are finished on both sides. Also, due to the added length to the rear wall without the closets, I'm not sure I need any absorbtion for rear reflections at all.

Any thoughts? Good idea? Bad idea? I guess the acoustic treatment I had done in February will have to be redone, but perhaps not completely, maybe just augumented?

Cheers,
Thor
Logged

gullfo

  • Full Member
  • ***
  • Offline Offline
  • Posts: 133
Re: Surround?
« Reply #20 on: November 19, 2007, 12:35:48 pm »

if you can make the room larger, then i second that approach.
Logged
Glenn Stanton

www.runnel.com/

Sonovo

  • Sr. Member
  • ****
  • Offline Offline
  • Posts: 267
Re: Surround?
« Reply #21 on: November 19, 2007, 05:19:22 pm »

Cool,

I think I'll go that route. It will make everything nicer, more user friendly, customer  friendly and modern. A positive change all around.

So, if I want try hanging acoustical panels from ceiling tracks (rather like sliding doors, but not full length), where would I go to find something appropriate? Anyone making panels that look good from both sides?

Thor


gullfo wrote on Mon, 19 November 2007 15:35

if you can make the room larger, then i second that approach.

Logged
Pages: 1 [2]  All   Go Up